Premature exposure of dental implant cover screws. A retrospective evaluation of risk factors and influence on marginal peri-implant bone level changes.

Abstract

The objectives of this study were to identify risk factors associated with the premature cover screw exposure (pCSE) at dental implants and to evaluate the influence of a pCSE on peri-implant marginal bone level (MBL) change compared to non-exposed implants. Retrospective data assessment from 165 patients (mean age=54.0±14.4years) who received 395 submerged implants included demographic, health-related, and therapeutic variables which were analyzed for their respective impact. MBL change was detected at digital radiographs obtained from first- and second-stage surgeries. pCSE were detected in 43 patients (26.1%) and 53 implants (13.4%). An increased frequency of exposure was significantly associated with (I) male gender (p=0.012) at patient level and (II) the posterior region of the jaws (p=0.005), implant systems with platform-matching cover screws, and a vertical distance of ≥0.5mm between bone crest and the implant platform (both p<0.001) at implant level. The decrease in mesial, distal, and total MBL differed significantly (mean total=0.8±0.7 vs. 0.3±0.5; mean mesial=0.8±0.8 vs. 0.3±0.6; mean distal=0.8±0.8 vs. 0.3±0.6mm; p<0.001) between non-exposed and pCSE implants. Male patients, implants with platform-matched cover screws, or when placed supracrestally or in posterior sites revealed significantly more pCSE, resulting in significantly decreased peri-implant MBL compared with non-exposed implants. Patients with an enhanced risk of pCSE should follow frequent regular recalls during the healing period to enable for early diagnosis and intervention.